Reptiles and amphibians of Cumbria

Natterjack toad

Identification

Natterjack toads are smaller than the more widespread common toad, reaching a maximum length of around 10cm. Natterjack toads are identifiable by their pale dorsal stripe which resembles marram grass; it is probable that this aids camouflage. Females are larger than males, as is common with most amphibians. This species of toad has short legs which enable it to run rather than hop. This is an ideal adaptation for its habitat which often has a low covering of grass. The eyes have a horizontal pupil and a silvery-gold iris. The ground colour of this species is brownish or greenish, mottled with darker markings. Males have a large external vocal sac beneath the chin which inflates when calling. Natterjack toads are the loudest native amphibian in Britain and can be heard calling from over a mile away on a still night.

Natterjacks have been known to live 17 years in captivity but presumably this is shorter in the wild.

Habitat

Cumbria is fortunate in that roughly half of the entire UK population of natterjacks is located in the county. They are found mostly along the coast in fragmented populations, and also one inland location in the south of Cumbria. Typical habitat of this species is coastal dunes which contain areas which flood during the spring and summer months; this is where this species breeds and where the tadpoles develop.

Diet

Natterjack toads eat invertebrates, which they hunt for at night. Worms, beetles, spiders and similar animals are all on the menu for this amphibian. Once captured, the prey is crushed in the jaws and swallowed whole.

Reproduction & hibernation

The breeding season starts late for this species; April to June most years, although spawn can be laid as late as August in particularly unfavourable years. Breeding pools are often shallow, temporary bodies of water on sandy soils. Females visit ponds briefly and deposit 1,500 to 7,000 eggs arranged in a single strand. When initially laid the eggs are paired across the cord, as they are in the common toad, but after two or three days they separate and a single row of eggs is formed. This helps to distinguish the eggs of the two species from each other.

Spawn hatches in about a week and the tadpoles are very small when they emerge. Metamorphosis is exceptionally quick and the toadlets are under one centimetre when they emerge from the water. Yet again, this is a great adaptation for the unreliable water pools they develop in.

Most natterjacks breed for the first time at four years old, but some are able to at just three years old. At this time they are generally 5-6cm long.

Hibernation is often from September or October to March in Cumbria. These toads burrow down in the sand dunes to escape freezing temperatures and only emerge when the night-time temperatures are warm enough, temporary ponds are full enough, and there will be plenty of food to eat.